Carburetor



Jun; 22, 1937. .M. J. B BARBAROU ,3 CARBURE'F'OR 7 Original Filed July 28, 1950 2 Shee'{cs-Sheet l IN VEN TOR.

B {Var/215 J-B Barbarau A TTORN M. J. B. BARBAROU CARBURETOR June 22, 1937.

Original Filed July 28, 1930 2 Sheets-Sheet 2 INVENTOR. Manusffibarbarm BY ATTORNEY Patented 1m 22,1937

UNITED STATES PATENT OFFICE' oimmmnron of Illinois Application July 28, 1930, Serial No. 471,257. In

France August 6, 1929.

18 Claims.

fuel which spills over the body 'of plane and l 10 constitutes a very serious fire hazard, particularly when the plane is flown inverted; and third,

they are complicated, having a multiplicity of jets and adjustments which add to the expense of manufacture and difficulty of operation.

It is an object of my invention to provide a carburetor especially adapted for high altitude flying which will not frost and clog up at high altitudes.

Another object of my invention is to devise a carburetor in which the liquid fuel is completely sealed from contact with the air except as it issues from the main jet, thus reducing the possibility of leakage to a minimum.

Another object of my invention is to devise a carburetor especially, adapted for flying inverted and at steep angles of inclination, by providing a positive pressure feed for the liquid fuel regulated by a pressure diaphragm without the use ofthe conventional float chamber.-

Still another object of my invention isto provide a carburetor adapted for all conditions of airplanes which is extremely simple in construction, having only one jet for all purposes, thus reducing cost and difliculty of operation.

With these and other objects which may be incident to my improvements, my invention consists in the combination and arrangement of elements hereinafter described and illustrated in the accompanying drawings, of which:

Figure 1 is a vertical cross section on the line ll of Figure '2 of a carburetor according to my invention,

Figure 2 is a plan view of same,

Figure 3 is a longitudinal section on the line 3--3 of Figure 2, and

Figure 4 is a plan of a modified form of my improved carburetor.

According to the form shown in Figures 1-3, the carburetor is of the horizontal type and comprises a cylindrical body I, having a flared intake mouth 2 and a reduced extension 3 constltuting a mixing chamber. In the body I, immediately adjacent the air inlet, there is a butterfly throttle valve 4 mounted upon a shaft 5 journaled in the walls of the body I as clearly Renewed J une" 20,

shown in Figure 3. Fixed upon one end of shaft is an operating lever 6 which is connected to a. throttle control adjacent the pilots seat (not shown). In the reduced section 3 is mounted the Venturi throat I in the center of the narrowest zone of which is located the main jet nozzle 8.

The size of the orifice in this nozzle is regulated by a tapered needle 9 which is moved relative to the nozzle by the rotation of a nut l0 engaging a screw thread II on the stem of the needle and also by the rotation of the needle stem within the nut l0, by a pinion l2 fixedly mounted on the .end of the needle stem. Pinion i2 meshes with, and is actuated by, toothed sector l3 which is fixed to the throttle shaft 5, so that as the throttle is opened the pinion I0 is rotated and the needle 9 partly withdrawn from the nozzle 8 thus opening the nozzle orifice in proportion to the throttle opening.

It will be noted that the pinion l2 makes approximately one complete revolution during the opening of the throttle 4. The amount by which the needle 9 is then withdrawn from nozzle 8 is determined by the pitch of the thread Ill and may be varied as desired by-substituting needles whose threads have different pitches. Also the rate of opening of nozzle 8 can be varied by substituting needles of different tapers.

To insure meshing of the pinion l2 with sector l3 at all times, the former is made approximately twice the width of the latter to compensate for its longitudinal movement.

Integral with the nut in is an arm 14 movable in a slot in the cap l5 which holds nut III in its seat [6. This armis connected at its outer end to the altitude mixture control in the cockpit (not shown) and by rotating I0 moves needle 9 inwardly or outwardly of the nozzle 8 and thus increases the ratio of liquid fuel to air to compensate for changes in density of the air with altitude.

It will be observed that in the foregoing arrangement the altitude mixture adjustment is effected with the same valve and nozzle that control the flow to the main jet; In this way,

I avoid the use of multiple jets and valves and thus reduce to the minimum the chance for leakage' of liquid fuel out of the carburetor.

Other means may obviously be employed for connecting and coordinating the movement of the needle valve with the throttle valve. Thus, in Figure 4 I have illustrated a modification wherein the connection between the throttle and needle valves, instead of being positive, as in Figure 2, is non-positive so. as to allow any desired variation between the movements of these two valves. For .this purpose, instead of mounting the sector gear direct on the throttle shaft, I employ a smaller sector l1, pivoted on a stud 8, attached to the wall of body I, and carrying an arm i 9 on the. end of which is a roller 28 held in contact by a spring 2| with a cam surface 22 of an arm 23 fixed on throttle shaft 5. By this arrangement the relative movement of the needle valve 8 with reference to the throttle 4 may be readily varied by varying-the contour of the cam 22.

Liquid fuel is supplied to the nozzle 8 by a constant pressure pump 68 through a pipe 24, chamber 25 and conduit 26. Chamber 25 is hermetically sealed by a flexible diaphragm 21 held tightly to an annular seat 28 by a cover 29 secured thereto with screws 38. On the other side of the diaphragm 21, the cover 29 forms a chamber 3| which may either be in communication through a pipe 32 with the interior of body posterior to throttle valve 4, as in Figure 3, or in direct communication through a vent 33 with the outside atmosphere, as in Figure 4. The admission of liquid fuel to the chamber 25 is controlled by a check valve 34 adapted. to bear on a seat 35.

The stem 36 of valve 34 is connected at 31 to an oscillating lever 38 pivoted at one end38 to the wall of chamber 25 and carrying at its other end a knuckle 48 which is engaged by a hook 4| secured to the center of diaphragm 21 so that the free end of lever 38 moves inunison with the center of diaphragm 21. On the other side of diaphragm 21 in the chamber 3l, the diaphragm has a similar hook 42 engaging one arm of a bell crank lever 43 which is pivoted at 44 to the wall of chamber 3| and carriesat the end of-its other arm a counterweight 45.

As, stated above, chamber 3| may be in communication with the outside air through a vent 33 so that atmospheric pressure prevails at all times in chamber 3|. In this case the operation of the carburetor is as follows:

The liquid fuel which is contained in chamber 25 and in conduit 28 exerts a predetermined pressure on the diaphragm 21, which pressure is balanced by the atmospheric pressure and by the force of lever 43 with coimterweight 45 acting on the other side of diaphragm 21. It is obvious that this equilibrium is maintained regardless of the position and orientation of the carburetor for the reason that with any change of position from that shown in Figure l the force of gravity will act equally on the liquid column in chamber 25 and conduit 26 and the counterweight 45. when.

liquid fuel is drawn from nozzle 8 by the suction of the engine, a reduced pressure is created in chamber 25 and the diaphragm 21 will tend to open check valve 34 through the medium of lever 38. When the suction on nozzle 8 is less than the pressure developed by the fuel pump in pipe 24, check valve 34 will seat and cut ofl further supply of liquid fuel to chamber 25.

There is, therefore, a substantially constant pressure on the liquidfuel in nozzle 8 and as, the area of the orifice at the end of the nozzle is varied according to the position of the throttle valve 4 by the arrangements shown in Figure 2 or 4,

there will always be a supply of liquid fuel proportional to the supply of air, and ifthe arrangement shown in Figure 4 be used, the ratio between the fuel dispensed by nozzle 8 and the air passed by throttle 4 need not be constant but may be made to vary as desired by the configuration of cam surface 22.

As stated with reference to Figure 3, chamber 3| may be in communication through pipe 32 with body I of the carburetor. In the preferred construction shown in Figure 3, this communication is established through an auxiliary chamber 46,

calibrated orifice 41 and conduit 48. Chamber 46,

further communicates with'the mixing chamber 3' through a pipe 49 which leads from the upper end of chamber 46 to the entrance of the Venturi throat 1. The flow of air through and the consequent pressure in chamber 46 is controlled by a rotary cut-off valve 58 which is fixed to throttle shaft 5 and disposed in chamber 46 so as to open and close communication with pipe .49 as clearly shown in Figure 3. By this arrangement, it is obvious that as the throttle 4 is opened the end of pipe, is gradually uncovered by valve 58 and communication of auxiliary chamber 45 with mixing chamber 3 is established.

The time and rate at which valve 58 uncovers pipe 48, with reference to the opening of throttle 4, can manifestly be fixed as. desired by suitably arranging the relative angular positions of valves 4 and 58 on shaft 5 and by giving a suitable bevel to the edge of valve 58.

The operation in this case is as follows:

If the profile of rotary cut-oif valve 58 is so adjusted that the vacuum in the chamber 3| is weak at high speed and strong at slow speed, the

needle 9 may be arranged to permit a greater passage of liquid fuel than if the vacuum in chamber 3| remained weak at slow speed since the vacuum in chamber 3| is partly determined by that prevailing at the end of nozzle 8. Moreover, when throttle valve 4 is' opened, the nozzle 8 produces an injection of liquid fuel because, owing to the vacuum being reduced in chamber 3|, the diaphragm 21 is displaced with respect to chamber 25. I

The advantages of my carburetor are obvious. There is nowhere any free liquid fuel in communication with the air except at the outlet of the main nozzle which is always closed when the throttle is closed. I

There is no possibility of frosting as the throt-- tle valve is mounted anterior to the nozzle and the liquid fuel is atomized when leaving the nozzle and is vaporized only in the manifold or cylinders if the carburetor is mounted directly on an inlet to the cylinders. The carburetor is well adapted for aviation use since it operates indefinitely and with equal facility in all positions. It also considerably reduces the danger of fire since there can be no leakage of liquid fuel. It is also simple to manufacture and easy to operate.

It is also to be understood that my invention is by no means limited to the constructional forms shown and described herein as these have been selected only' for the purposes of illustration.

said nozzle under'a pressure always substantially greater than atmospheric and means responsive to the movement of the throttle for controlling the effective cross section of said nozzle, said first mentioned means being operative to maintain said pressure substantially constant regardless of the position of the carburetor. v

2. In a carburetor, a liquid fuel nozzle, means for supplying liquid fuel to said nozzle under positive pressure, andmeans for regulating the pressure on the liquid fuel supply including a diaphragm subject to atmospheric pressure and the action of a counterweight on one side and the weight of the liquid fuel supply column on the other side of said diaphragm.

3. In a carburetor having a throttle, a liquid fuel nozzle, means positively actuated in accordance with the movements of said throttle toenlarge the effective cross section of said nozzle in proportion to the opening of said throttle, and means for modifying the action of said enlarging means for changes in altitude. I

4'. In a carburetor having a mixing chamber, a liquid fuel pressure regulating means comprising a fuel chamber and an air chamber in pressure responsive relation to said fuel chamber, and means including a valve positively controlled by the movements of said throttle, for varying the pressure in said air chamber so as to make it bear any desired ratio to the airpressure in said mixing chamber.

5. In a carburetor havinga liquid fuel nozzle, means for supplying liquid fuel to said nozzle at a constant pressure above atmospheric, said means comprising a flexible diaphragm subjected to the pressure of the liquid fuel on one face thereof, a conduit connecting the other face thereof to the carburetor adjacent the fuel nozzle, and a valve in said conduit positively actuated in accordance with the position of the throttle. Y

6. In a carburetor, a fuel nozzle, means for supplying fuel to said nozzle under positive pressure, and means for controlling said pressure including a diaphragm subjected to fuel pressure urging it in one direction, and a counterweight normally urging it in the other direction.

7. In a carburetor, a fuel nozzle, and means for controlling the pressure of fuel supplied to the nozzle comprising a diaphragm having one of its faces subjected to the pressure of said fuel urging the diaphragm in one direction and having its other face subjected to fluid pressures existing in the carburetor, and a counterweight normally urging the diaphragm in a direction opposite to the fuel pressure on the diaphragm.

8. In a charge forming device, a fuel mixture passage, a throttle controlling the same, a fuel nozzle positioned to discharge into said mixture passage posterior to the restriction formed by said throttle,a source of fuel under superatmospheric pressure, a conduit connecting said source of fuel to said nozzle, a pressure regulating member in said conduit, and means controlling said pressure regulatingmember comprising a member simultaneously subjected to the pressure of the liquid fuel in said conduit and to varying subatmospheric pressure within said mixture passage.

9. In a charge forming device, a fuel mixture passage, a throttle controliing the same, a fuel nozzle positioned to discharge into said mixture passage, a source of fuel under superatmosphei ic pressure, a conduit connecting said source of fuel to said nozzle, a pressure regulating member in said conduit, and means controlling said pressure regulating member comprising a member simultaneuosly subjected to the pressure of the liquid fuel in said conduit and to varying subatmospheric pressure within said mixture passage; the effect of subatmospheric pressure upon the pressure responsive member being modified in accordance with the position of the throttle.

10. In an anterior-throttle carburetor, an induction passage, a throttle controlling the same,

a fuel nozzle discharging into said induction passage and controlled by the position of said throttle substantially throughout its range of movement, means for supplying fuel at a substantially constant pressure above atmospheric, a conduit connecting said supplying means to said nozzle, a valve in said conduit, and control means for said valve comprising a member responsive to prespressure above atmospheric, a valve controlling 12. In a charge forming device, a fuel mixture passage having an air inlet and a venturi, a throttle forming a variable restriction in said passage, a fuel nozzle discharging into the mixture passage at a point subject to the restricting effect of said throttle, a fuel reservoir connected to said nozzle, a pump for supplyingfuel to said reservoir at a pressure above atmospheric, a valve controlling the communication between said pump and said reservoir, and control means for said valve comprising a movable member responsive to pressure in said mixture passage at the restriction of said venturi and to pressure anterior to said throttle.

13. Fuel supply means for an internal ombustion engine, comprising a mixture paks ge including a venturi, a throttle anterior to said venturi controlling the mixture passage, a fuel nozzle discharging at the throat of said venturi, a fuel reservoir connected to said nozzle, a source of fuel supply at a substantially constant superatmospheric pressure, a valve controlling the flow of fuel from said source to said reservoir, and control means for said valvecomprising a pressure responsive member, a pressure chamber communicating with said pressure responsive member, a conduit connecting said pressure chamber with a source of substantially atmospheric pressure, a second conduit connecting the pressure chamber with asource of subatmospheric pressure associated with the engine, and means 'controlled by said throttle substantially throughout its range of movement for controlling one of said conduits.

14. In a fuel supply device for an internal combustion engine, a charge forming device having a fuel mixture passage and a fuel nozzle therein, a pump forming a source of fuel under substantially constant superatmospheric pressure, a conduit connecting the outlet of said pump to said 'therebetween; a pump forming a source of fuel under substantially constant superatmospheric pressure,'a conduit connecting the outlet of said pump to said nozzle, a valve controlling the outlet of said pump, and control means for said valve comprising a member influenced by pressures existing at said air inlet and at said venturi.

16. In a fuel supply device for an internal combustion engine, a charge forming device havinga fuel mixture passage and a fuel nozzle therein,

said fuel mixture passage being controlled by a manually operated valve, a pump forming a source of fuel under substantially constant superatmospheric pressure, a conduit connecting the outlet of said pump to said nozzle, a valve con trolling the outlet of said pump, and control means for said valve comprising a member responsive to the resultant of pressures at two spaced points in said mixture passage, said resultant being modified by the position of said manually operated valve.

17. In a charge forming device for an internal ing on said movable wall to balance the weight,

of the column of fuel located between-the fuel nozzle and the reservoir at all positions of the carburetor.

MARIUS JEAN BAP'I'ISTE BARBAROU. 20 

